THE STRUCTURE AND DYNAMICS OF SILICA POLYMORPHS USING A 2-BODY EFFECTIVE POTENTIAL MODEL

The performance of a recently proposed two-body potential model for SiO2 [van Beest et al., Phys. Rev. Lett. 64, 1995 (1990)] was critically evaluated through the calculation of the static and dynamical properties of several polymorphs of SiO2 using molecular dynamics methods. It was found that the calculated static structures are in excellent agreement with experiments. In particular, the pressure-volume equations of state for alpha-quartz, cristobalite, and stishovite, the pressure-induced amorphization transformation in alpha-quartz and thermally induced the alpha --> beta transformation in cristobalite are well reproduced by this model. The calculated vibrational spectra are in fair agreement with experiments. The strengths and the weaknesses of the potential will be presented and discussed.